Stereo depth cameras are well-known and are often used to measure a distance from an object. One such measurement device includes a projector and a camera. In such a device, the projector projects a known pattern image on an object (e.g., a scene), and am image of the object upon which the image is projected is captured by the camera. From the captured images, depth information may be determined. One technique for determining depth in such devices is through the use of triangulation. Thus, images of objects are captured and measurements are taken to determine depth information.
There is need to calibrate the intrinsic and extrinsic geometric parameters of an active coded light passive triangulation system including the infrared (IR) projector, the IR camera, and the red, green, and blue (RGB) camera. Typically, the process is performed on a per-unit basis during the assembly. Such calibration is usually handled using a “multi-view” approach that includes presenting to the camera a planar target with detectable features, such as a checkerboard, and capturing data at a set of unknown orientations. This approach has several major disadvantages. First, the need to automatically capture several views of the target increases the acquisition time and requires complicated mechanics. Second, the feature detection quality may be greatly compromised by the low modulation transfer function (MTF) of the IR camera, affecting the quality of the entire process. For example, the IR camera may not be able to accurately detect the landmark points in the target object.